Thirty per cent of customers subscribe to a premium service. Of the premium subscribers, 80% use the mobile app each week. Of the other customers, 20% use the app each week.
Find the probability that a randomly selected customer uses the app in a given week.
Given that a customer uses the app, find the probability that the customer is a premium subscriber.
Given that a customer does not use the app, find the probability that the customer is not a premium subscriber.